From ef3231380786b172f14f9a3275087938775ea2ee Mon Sep 17 00:00:00 2001
From: Manav Rathi <manav@mrmr.io>
Date: Wed, 31 Jul 2024 14:04:29 +0530
Subject: [PATCH] x4

---
 web/apps/cast/src/services/pair.ts            |  3 +-
 web/packages/new/photos/services/ml/worker.ts | 31 +++++++++++++++----
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/web/apps/cast/src/services/pair.ts b/web/apps/cast/src/services/pair.ts
index b5646698cc..287122c456 100644
--- a/web/apps/cast/src/services/pair.ts
+++ b/web/apps/cast/src/services/pair.ts
@@ -82,7 +82,8 @@ export const register = async (): Promise<Registration> => {
 
     // Register keypair with museum to get a pairing code.
     let pairingCode: string | undefined;
-    // TODO: eslint has fixed this spurious warning, but we're not on the latest
+    // [TODO: spurious while(true) eslint warning].
+    // eslint has fixed this spurious warning, but we're not on the latest
     // version yet, so add a disable.
     // https://github.com/eslint/eslint/pull/18286
     /* eslint-disable no-constant-condition */
diff --git a/web/packages/new/photos/services/ml/worker.ts b/web/packages/new/photos/services/ml/worker.ts
index 5de8c08390..ca5f112468 100644
--- a/web/packages/new/photos/services/ml/worker.ts
+++ b/web/packages/new/photos/services/ml/worker.ts
@@ -288,15 +288,34 @@ const indexNextBatch = async (
     // Nothing to do.
     if (items.length == 0) return false;
 
-    // Index, keeping track if any of the items failed.
+    // Keep track if any of the items failed.
     let allSuccess = true;
-    for (const item of items) {
-        try {
-            await index(item, electron);
-        } catch {
-            allSuccess = false;
+
+    // Index up to 4 items simultaneously.
+    const tasks = new Array<Promise<void> | undefined>(4).fill(undefined);
+
+    let i = 0;
+    while (i < items.length) {
+        for (let j = 0; j < tasks.length; j++) {
+            if (!tasks[j]) {
+                tasks[j] = index(ensure(items[i++]), electron)
+                    .then(() => {
+                        tasks[j] = undefined;
+                    })
+                    .catch(() => {
+                        allSuccess = false;
+                        tasks[j] = undefined;
+                    });
+            }
         }
+
+        // Wait for at least one to complete (the other runners continue running
+        // even if one promise reaches the finish line).
+        await Promise.race(tasks);
+
+        // Let the main thread now we're doing something.
         delegate?.workerDidProcessFile();
+
         // Let us drain the microtask queue. This also gives a chance for other
         // interactive tasks like `clipMatches` to run.
         await wait(0);